Tire condition monitoring systems have conventionally been known which monitor quantities of or values representing tire conditions (e.g., air pressure, temperature, etc.) for pneumatic tires. A tire condition monitoring system is provided with a tire condition acquisition device which is disposed in a hollow portion of a pneumatic tire and acquires quantities of tire conditions (e.g., air pressure, and temperature) and a monitoring device which monitors quantities of tire conditions by receiving radio waves from the tire condition acquisition device.
If the tire positions in the tire condition acquisition device are moved because of tire rotation or the like, the registration information associating the sensor ID of the tire condition acquisition device and the tire positions has to be updated. It is, therefore, preferable to be able to easily update the registration information. Conventional tire condition monitoring systems related to this problem are disclosed in Japanese Patent Nos. 4764479B and 4857783B, as well as in Japanese Unexamined Patent Application Publication Nos. 2008-74223A and 2010-125878A.